Tight rifle chambering - Problems?

[Ash]

I have a Mossberg 810 centerfire in .30-06 that I recently acquired. It is in excellent condition and if far nicer than anything at Wallyworld these days (hinged floor plate, walnut stock, deep bluing, open sights, etc.). This model has four locking lugs, two in tandem opposed to each other aligned in a similar way to the Savage 110 or Remington 700, but with four lugs instead of two. I decided to test function to see if it fed reliably and found it chambered, but somewhat tightly. I then chambered a go headspacing gauge and found it tought to close. I could close the bolt, but only with some force. I didn't strain, but the force was noticeable. I can only conclude that the chamber is tight. Now, this is a 30 year old rifle that has hardly been shot, if at all.

It closes on live ammo, but with a little force (something noticeable, but not with difficulty). It seems odd to have tight headspace on a rifle this old, except that it might just be unfired and came from the factory with tight headspace. Should I be concerned about headspace being too tight? For that matter, what should I expect from the rifle, all things being equal, with this headspace?

I have a second 810 in .30-06 and I could change out bolts. I did this, and the go gauge chambers just fine with the new configuration. However, I do not have a no go gauge so I can't check to make sure the new arrangement doesn't create excessive headspace. The informal test, with the tighter bolt in the other rifle, seems to indicate safety, and logic would indicate the same. Yet, momma didn't raise a fool so here I ask the questions.

Ash

 

[Onmilo]

Sounds like you may want to get a 30/06 chamber brush and give the chamber a good scrubbing before you do anything.
There may be light corrosion in the chamber, there may be a flake or burr in the chamber or on the bolt itself that needs to be corrected.

A flaw on the bolt can cause just as much problem as a short chamber.

What I am interested about is the brand of headspace guage you used to do your headspace check.

You do realize that to get the absolute and most correct use of the guage that the bolt of the weapon, any weapon, needs to be stripped of the extractor and ejector, probobly the firing pin too so you don't have a slam fire since I am guessing you aren't using action proving cartridges are you??

A stripped bolt will also allow you to 'feel' any irregularities in the action and the bolt as you cycle it down the raceway.

Headspace is critical, you should never try to guage one end of the limits without guaging the other end too.
In other words you really should have a no go guage too.

 

[Art Eatman]

I'll second the idea of a good scrubbing of the chamber and checking the bolt face. (I'm not familiar with that particular rifle. Is the ejector a spring-loaded button, built into the bolt? If so, is it free to be pushed all the way back where it's flush with the face of the bolt?) If that doesn't bring about a normal effort at closing the bolt, it's gunsmith time. No big deal to run a chambering reamer into it.

Art

 

[Ol` Joe]

Onmilo gave some good advice. You should always strip the bolt before trying go/no go gauges and a dirty chamber in a older gun can bind things up some. Be sure to keep a dab of grease on the contact surfaces of the lugs to prevent galling and help smooth the operation.

What ever you do don`t switch bolts! None of the manufactures provide bolts as a repair part to the public that I`m aware of. They are not a "drop in" part and void any warrenty or liability Mossberg provides. The headspace, trigger, and saftey all can be altered by switching some bolts out. A tight chamber as long as it falls in spec and chambers ammo hurts nothing and acually aides accuracy.

 

[Ash]

The rifle has been out of production for 25 years, and this one is from the late 1960's, so warranties are of no consequence. The interchanging of bolts is a neat little trick I learned with milsurps, especially Mosins. If the Mosin fails the field gauge, then you can change out bolt heads until it passes. Easy fix. If I were to interchange bolts, as long as both rifles passed head spacing, that would be much cheaper than having a smith work on either rifle.

The bolt head looks very much like a Remington 700, save for the four lugs instead of two. It has a plunger-type ejector and an extractor just like the Remington.

Now, I did a test last night. After cleaning out the chamber with a brush, I marked a case with a permenant marker, entirely around the shoulder. I then chambered the round. As before, the round chambered, but with some tightness as the bolt handle closed, but it closed none-the-less. When I ejected the round, the marking was rubbed off in a very narrow line around the entire base of the shoulder, (where the shoulder narrows towards the neck, at the case side, not neck side). I suppose this is the contact point between the shoulder and the chamber. As it is a clear line all the way around, I would assume the issue wouldn't be debris in the chamber missed in my cleaning last night. I will try the head space gauge again after removing the extractor and ejector (didn't have time last night, with a 7 month old needing the attention that such fellows require) when I can. But these are the results I have as of now. Does this shed any further light on the subject?

Ash

 

[Ol` Joe]

Are these reloads you are trying to chamber? It sounds like you might be pulling the shoulder out with the expander ball when sizeing the case. Be sure to lube the inside of the case neck when sizeing, and if your expander still feels like it`s dragging still try polishing the ball with some fine grit emery while spinning it with a drill or dremal. Don`t remove metal if you polish just buff it a little.

Changing the bolt increased headspace and allowed the cartridge to chamber more easily. I agree you can swap them out to find one that works but they are meant to be fitted parts in commercial rifles, note the serial # on them. The military rifles have much looser tolerance then comercial and are built to allow for easier repair. As I said earlier the bolt also controls trigger engaugment and it also can change it along with chamber headspace. Some action mounted safties are also sensitive to their relationship with the bolt. As far as I know Winchester, Remington, ect won`t sell bolts as repair items to the public, your gunsmith is included.

 

[Ash]

The ammo is Winchester Factory Supreme High Velocicity 180 grain soft points. The safety is bolt mounted, so that's okay. If a bolt change-out did occur, I would do the bump test to make sure the adjusted trigger still was safe.

Now, for the sake of argument, what danger is involved if the chamber is a bit tight? I can chamber the round, the bolt seats completely down and is fully locked. As I said, it closes tightly, but will close completely. I am under the impression that peak pressure is or may be higher. Is that the primary danger? Is that a danger? How might that accuracy?

Ash

 

[Onmilo]

A tight chamber is far more desirable than a loose chamber.
As long as you can open and cycle the bolt after firing without having to beat the bolt open with a rawhide hammer the rifle will be safe.

 

[Gewehr98]

Do you reload?

If the rifle has a tight chamber, but fired rounds extract easily, then you're still in good shape. You can simply neck size your fired rounds, which will greatly enhance your case life. If you're committed to factory ammo, and the chamber is so tight that the stuff refuses to chamber, then you may have a problem that requires some assistance of a gunsmith with a finish reamer to just "clean up" the chamber a wee bit.

For new handloads, a full-length sizing die set to bump the shellholder on maximum stroke (which bumps down the shoulder just a smidgen) may be all you need to chamber rounds easily. If not, then it's either cleaning up the chamber or going with the shorter shellholders associated with small-base sizing dies.

I have a .30-06 Belgian Browning BAR that has a tight chamber. I'd send it back to Browning, but I've found that the rifle works beautifully with my handloads using small-base full-length resizing dies.

 

[Ash]

Well, I don't reload as of yet, though I do have some dies and a single press, along with a powder measure (without the hopper) that I inherited from my grandfather, who had recieved it all from my great uncle, who died in 1977. I believe it is all lyman stuff, and I admit it has piqued my interest. I realize it might be cheaper to buy new stuff than to try to retrofit or otherwise use what I have. That is for another day.

The factory ammo I have chambers, but with noticeable force when closing the bolt. It isn't tough to close, but with more force than what I consider normal (or as compared with the other Mossbergs I have).

Ash

 

[Ash]

Interesting partial resolution of the problem. It seems the Winchester Supreme ammo I was trying to chamber is a tad long. I chambered some regular Winchester Super X soft points and they went in and closed just fine. I then pulled a second box of the Supremes and got the same chamber tightness as before. I can only conclude that the Supreme brass is ever so slightly longer than the Super X. Perhaps to enhance accuracy?

Ash

 

[Art Eatman]

In the FWIW department, I've killed over 20 deer with the '06, using 150-grain ammo.

With a press and dies, the only major item you need is a powder scale. Little stuff, of course, like a powder funnel and a loading block to hold the primed cases when filling with powder. (I've been cheapskate enough to just take a piece of 2x4 and drill a bunch of half-inch holes. ) Chamfering tool for putting a bit of an angle on the inside of the case neck. I ground a screwdriver to fit the primer pocket; just twirl the shaft to clean out primer residue.

The '06 can be happy with a broad range of powders; I've used mostly 4064 for over fifty years, now...I'm happy with 150-grain Sierras for "basic Bambi".

If you get unhappy with that tight chamber, buy a reamer from Brownell and gently clean the chamber that last couple of thousandths of an inch.

Art

 

[Ash]

I'm starting to think that I should go ahead and step into the reloading world. I've saved all the boxer brass I have ever fired in the event I wanted to reload, particularly the 7.62x54R. Investment may be very small if my equipment is still standard.

Thanks to all who offered help and suggestions.

Ash